Hacker News Reader

Comment by njibhu | Hacker News Reader

This article from Crucial probably explains the two arguments: https://www.crucial.com/articles/about-memory/difference-bet... But their conclusion is that practical latency has indeed decreased over the last 15 years.

View on HN

After looking at the table, I am ready to swallow my pride. Looks like practical latencies have changed a tiny bit. So me and the person I replied to originally were both wrong

Also note that practical non-high-capacity DDR4 setups reach 3600 CL16. That's way faster than the 3200 CL22 they gave at the bottom.

You were wrong about the memory latency¹ increasing, but the memory latency² has increased (substantially) for most systems, while the memory latency³ has indeed decreased. In general, the memory latency¹ has not improved much. Of course, the memory latency⁴ has greatly increased, due to the clock frequency being increased so much to enable the higher bandwidth, while the memory latency¹ stayed mostly the same.

[1] as in: access latency of the DRAM [2] as in: how long does a CPU memory read which is _not_ cached take [3] as in: how long does a CPU memory read on average take [4] as in: CL

No, I was right. Not that it matters, feel free to replace latency with bandwidth. Or replace it with nothing and focus on capacity. It's a blip on my point, which is that the architecture has changed considerably to allow for progress in other areas.

Reply on news.ycombinator.com